templately / includes / Utils / Response / RetryPolicy.php

RetryPolicy.php in Templately – Elementor & Gutenberg Template Library: 6500+ Free & Pro Ready Templates And Cloud! 3.8.0, at includes/Utils/Response/RetryPolicy.php

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1	<?php
2
3	namespace Templately\Utils\Response;
4
5	/**
6	* When an outbound cloud request is worth repeating (spec 043 / PRD PHP-1).
7	*
8	* `Http::post()` retried on `WP_Error` only, three times, **with no delay at
9	* all** — a tight loop. That is the worst possible shape: it misses every
10	* retryable HTTP status (a 502 from a restarting upstream was final), and for the
11	* transport failures it did catch it fired three requests within milliseconds at
12	* a server that had just failed to answer one.
13	*
14	* Decisions live here rather than in the client so the outbound retry and the
15	* `retryable` flag the UI shows a Retry button for cannot disagree.
16	*/
17	class RetryPolicy {
18
19	/**
20	* Attempts AFTER the first. Beyond this the user is better served by an error
21	* they can act on than by a request that keeps not finishing.
22	*/
23	const MAX_ATTEMPTS = 3;
24
25	const BASE_DELAY_MS = 300;
26	const MAX_DELAY_MS = 5000;
27
28	/**
29	* HTTP statuses worth repeating.
30	*
31	* All transient by nature: a gateway restarting, a worker timing out, an edge
32	* dropping the connection. Deliberately NO other 4xx — a 401 or a 422 fails
33	* identically however many times it is sent.
34	*/
35	private static $retryable_statuses = [ 408, 502, 503, 504, 522, 524 ];
36
37	/**
38	* @param mixed $response A `wp_remote_*` result.
39	* @param int $attempt 0 for the first failure.
40	* @return bool
41	*/
42	public static function should_retry( $response, $attempt ) {
43	if ( $attempt >= self::MAX_ATTEMPTS - 1 ) {
44	return false;
45	}
46
47	// Transport failure — DNS, refused, reset. Worth another attempt.
48	if ( is_wp_error( $response ) ) {
49	return true;
50	}
51
52	$status = (int) wp_remote_retrieve_response_code( $response );
53
54	// A 429 is NOT auto-retried. `Retry-After` says when to come back, and
55	// looping is precisely what the server is asking us to stop doing; the
56	// normalizer surfaces it with the delay so the caller can honour it once.
57	return in_array( $status, self::$retryable_statuses, true );
58	}
59
60	/**
61	* Backoff in MICROseconds, ready for `usleep()`.
62	*
63	* Exponential with full jitter. The jitter matters more than the curve: every
64	* site that failed on the same upstream blip would otherwise retry in the same
65	* instant and recreate the load that caused it.
66	*
67	* Filterable so tests do not sleep.
68	*
69	* @param int $attempt
70	* @return int
71	*/
72	public static function delay( $attempt ) {
73	$exponential = self::BASE_DELAY_MS * pow( 2, max( 0, $attempt ) );
74	$capped = (int) min( $exponential, self::MAX_DELAY_MS );
75	$jittered = wp_rand( 0, $capped );
76
77	/**
78	* Backoff before the next outbound retry, in milliseconds.
79	*
80	* Return 0 to disable sleeping (what the test suite does).
81	*
82	* @since 3.7.0
83	* @param int $jittered Milliseconds.
84	* @param int $attempt 0 for the first retry.
85	*/
86	$delay_ms = (int) apply_filters( 'templately_http_retry_delay', $jittered, $attempt );
87
88	return max( 0, $delay_ms ) * 1000;
89	}
90
91	/**
92	* Sleep for the computed backoff. No-op when the filter returns 0.
93	*
94	* @param int $attempt
95	* @return void
96	*/
97	public static function wait( $attempt ) {
98	$microseconds = self::delay( $attempt );
99
100	if ( $microseconds > 0 ) {
101	usleep( $microseconds );
102	}
103	}
104	}
105